a-a a-c a-t aaa aac aad aaf aat ac- aca acc acd acf act ad- ada adc add adf adt af- afa afc afd aff aft at- ata atc atd atf att c-- caa cac cad caf cat cca ccc ccd ccf cct cda cdc cdd cdf cdt cfa cfc cfd cff cft cta ctc ctd ctf ctt daa dac dad daf dat dca dcc dcd dcf dct dda ddc ddd ddf ddt dfa dfc dfd dff dft dta dtc dtd dtf dtt faa fac fad faf fat fca fcc fcd fcf fct fda fdc fdd fdf fdt ffa ffc ffd fff fft fta ftc ftd ftf ftt taa tac tad taf tat tca tcc tcd tcf tct tda tdc tdd tdf tdt tfa tfc tfd tff tft tta ttc ttd ttf ttt